SOD1 and amyotrophic lateral sclerosis: With the exception of the roughly 20% of familial cases and less than 10% of sporadic cases of ALS attributable to mutations in the superoxide dismutase 1 (SOD1) gene (Andersen and Al-Chalabi, 2011) both sporadic and inherited forms of ALS are characterized by the aggregation of the nuclear proteins tar DNA binding protein 43 (TDP-43) or fused in sarcoma (FUS).